Laminated formed body and method of manufacturing the formed body

ABSTRACT

A laminated and molded body obtained by coextruding and molding at least two kinds of resin materials is preferable as a blow-molding aimed preform, a direct-blow molded bottle, a tube, or a blow molded tube, and has at least one layer constituted of a colored layer having a thickness continuously or intermittently varied in a direction parallel to the extruding direction of the at least one layer and/or in another direction intersecting the extruding direction, thereby enhancing the gradation effect.

BACKGROUND ART

1. Technical Field

The present invention relates to a laminated and molded body such as ablow-molding aimed preform and a direct-blow molded bottle which areduly obtained by using a plurality of kinds of synthetic resins asmaterials and by coextruding them, and intends to bring about avariation of the color tone of the laminated and molded body to therebyfurther improve the aesthetic appearance thereof. The present inventionfurther relates to a manufacturing method for manufacturing such alaminated and molded body.

2. Related Art

As containers made of synthetic resin for accommodating cosmetics or thelike therein, there have been numerously used molded articles such asobtained by injection molding or blow molding synthetic resins, from astandpoint to attain a suitable mass-production and a reducedmanufacturing cost. However, most of such molded articles are monotonousor have color tones of less variation, thereby resulting in a stillinsufficient aesthetic appearance of containers.

Thus, as described in JP-A-2000-117820, for example, it has beenrecently proposed to adopt such a technique to attain a variation ofcolor deepness to be given to a container, for achieving a so-calledgradation effect to thereby enhance the decorative effect of thecontainer.

The technique described in the above publication is to previouslyprovide a parison with a wall thickness difference at the time ofinjecting a translucent colored resin, and then blow molding theparison, to thereby cause the parison to have a partially different wallthickness. According to this technique, it has been believed to be ableto attain a pattern based on a color deepness without requiring anyspecific process and able to restrict the manufacturing cost to a lowerdegree.

However, the above-mentioned related art still has problems which shouldbe further improved, because the parison itself is provided with thewall thickness difference and thus the blow molded article also has thesame wall thickness distribution as the parison, thereby complicatingthe wall thickness control upon blow molding, because those particularlythin portions of the container have a so lowered rigidity that thestrength of the container is affected and that entrance of a gas (suchas oxygen) from the exterior into the container becomes easy, therebyleading to an anxiety about a shortened quality assurance period for thecontents accommodated within the container, because it is difficult tostably obtain molded articles having an excellent quality, and becausethe wall thickness of the dense color portion of the container is madeto have a greater wall thickness than required to thereby lead to anincreased cost when it is contemplated to preserve the rigidity of thewhole container.

DISCLOSURE OF THE INVENTION

It is therefore an object of the present invention to propose a novellaminated and molded body and a manufacturing method therefor capable ofsolving the above-mentioned problems in the related art.

The present invention provides a laminated and molded body obtained bycoextruding and molding at least two kinds of resin materials,characterized in

that at least one layer of the laminated and molded body comprises acolored layer having a thickness continuously or intermittently variedin a predetermined direction with respect to the extruding direction ofthe resin material of the colored layer (for example, in a directionparallel to the extruding direction and/or in another directionintersecting the extruding direction).

Further, the present invention provides a manufacturing method of alaminated and molded body to be formed by coextruding at least two kindsof resin materials, characterized in

that the method comprises the steps of:

extruding a colored layer as at least one layer of the laminated andmolded body, and

controlling an extruding amount of the resin material of the coloredlayer such that the colored layer has a thickness continuously orintermittently varied in a predetermined direction with respect to theextruding direction of the resin material of the colored layer (forexample, in a direction parallel to the extruding direction and/or inanother direction intersecting the extruding direction).

According to the present invention, it becomes possible to easily andassuredly obtain a laminated and molded body having an improvedaesthetic appearance, by adjusting the supplying amount of the resinmaterial forming the colored layer upon coextrusion. Further, thethickness of the resin material constituting the colored layer iscontinuously or intermittently varied along the predetermined direction,thereby allowing exhibiting such a visual effect, i.e., a so-calledgradation effect that the color deepness of the colored layer iscontinuously or intermittently varied in the predetermined direction.For example, when the thickness of the resin material constituting thecolored layer is varied in a direction parallel to the extrudingdirection, the color deepness of the colored layer is varied in thedirection parallel to the extruding direction. Alternatively, when thethickness of the resin material constituting the colored layer is variedin a direction intersecting the extruding direction, the color deepnessof the colored layer is varied in the direction intersecting theextruding direction.

It is desirable that the full thickness of the laminated and molded bodyis substantially uniform along the predetermined direction with respectto the extruding direction of the resin material. Namely, it isdesirable to control an extruding amount of the resin material of atleast one layer other than the colored layer, such that the fullthickness of the laminated and molded body is substantially constantalong the predetermined direction. In this case, the full thickness ofthe laminated and molded body is substantially uniform over the whole ofthe laminated and molded body even when the thickness of the coloredlayer is varied. Thus, there is never caused locally increased ordecreased wall thickness, thereby enabling to obtain a molded articlehaving a quality stabilized in terms of strength and to provide alaminated and molded body having an enhanced gradation effect with arestricted cost.

In the laminated and molded body having the above constitution, it isdesirable that the colored layer has a thickness varied within a rangeof 50% of the full thickness of the laminated and molded body.

The laminated and molded body according to the present invention isadvantageously applicable to a body portion of a container such as: ablow-molding aimed preform to be used upon biaxial-stretching blowmolding; a direct-blow molded bottle or direct-blow molded tube to beobtained by direct-blow molding a coextruded parison; and a tube.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be described hereinafter more in detail withreference to the embodiments shown in the accompanying drawings.

FIG. 1 is an explanatory constitutional view of a laminated and moldedbody according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of an essential part of themolded body shown in FIG. 1.

FIG. 3 through FIG. 7 are enlarged views of essential parts forexplaining laminated structures in other embodiments of the presentinvention.

FIG. 8 is an explanatory constitutional view of a laminated and moldedbody according to a further embodiment of the present invention.

FIG. 9 is an enlarged cross-sectional view showing an essential part ofthe molded body shown in FIG. 8, in a developed state.

FIG. 10 is an explanatory constitutional view of a laminated and moldedbody according to a still further embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 exemplarily shows a blow molded article in a shape ofdual-layered bottle-type container according to an embodiment of thepresent invention, wherein reference numeral 1 designates a main bodyportion as an inner layer, and reference numeral 2 designates a coloredlayer arranged outside and integrally with the main body portion 1. Thecolored layer 2 has a thickness increased from a mouth portion of themolded article toward a bottom portion thereof, thereby graduallyincreasing the color density. Note, the main body portion 1 as the innerlayer has a thickness reduced from the mouth portion of the moldedarticle toward the bottom portion thereof, thereby achieving asubstantially constant thickness “t” over the whole of the laminated andmolded body.

The molded article shown in FIG. 1 is constituted as the containerhaving an improved gradation effect provided by a color tone graduallydeepened in a direction parallel to the extruding direction of themolded article, i.e., from the mouth portion toward the bottom portion,thereby remarkably improving the aesthetic appearance of the container.

In molding such a container, it is possible to use a multi-layercoextrusion die of a type for simultaneously merging different resinmaterials or a type for sequentially merging them.

In this respect, it is possible to adjust the color deepness in alaminated and molded body, by appropriately controlling an extrudingamount of a resin constituting the colored layer. Naturally, the thickerthe colored layer, the deeper the color, and vice versa. In case of thecontainer of FIG. 1 the essential part of which is enlargedly shown inFIG. 2, the colored layer 2 has a wall thickness distribution graduallyreducing from the bottom portion toward the mouth portion, while themain body portion 1 as the inner layer has a wall thickness distributiongradually increasing from the bottom portion toward the mouth portion.

Upon coextrusion, the thickness of the colored layer 2 is appropriatelyvaried by controlling the extruding amount of resin material, and thethickness of the main body portion 1 neighboring to the colored layer 2is also varied correspondingly thereto. Thus, the full thickness of thelaminated and molded body is kept substantially constant over the wholeof the laminated and molded body, thereby never causing such portionshaving extremely reduced or increased thicknesses, except for wallthickness changes due to the product shape.

As materials for constituting the laminated and molded body, it ispossible to use: an olefin-based resin such as polyethylene resin orpolypropylene resin; and a polyester resin such as a polyethyleneterephthalate resin (PET); and it is possible to use an ethylene vinylalcohol copolymer (EVOH), nylon or the like, as a barrier resin.

The laminated and molded body having the above structure can be molded,by adopting a molding apparatus having a flow passage for supplying aresin material corresponding to the main body portion 1 as the innerlayer and another flow passage for supplying a resin materialcorresponding to the colored layer 2 arranged outside and integrallywith the main body portion 1, and by coextruding these resin materials.

There will be explained hereinafter laminated and molded bodiesaccording to the other embodiments shown in FIG. 3 through FIG. 7.

As shown in FIG. 3, the laminated and molded body according to anotherembodiment of the present invention is allowed to be provided with afrosting layer 3 comprising a glossy material or frosted materialoutside the colored layer 2, thereby making it possible to providevariations of not only a color deepness but also a color tone.

Further, as exemplarily shown in FIG. 4 through FIG. 7, each of thelaminated and molded bodies according to the present invention can beprovided as an appropriate combination of: an adhering layer; and abarrier layer such as comprising EVOH or comprising meta-xylylene-groupcontaining polyamide, for restricting permeation of oxygen. Namely, in afurther embodiment of FIG. 4, there is arranged an adhering layer 4between the colored layer 2 and frosting layer 3 in the embodiment ofFIG. 3. In a still another embodiment of FIG. 5, there are successivelyarranged an adhering layer 4, a barrier layer 5 and another adheringlayer 4, between the main body portion 1 as an inner layer and thecolored layer 2 in the embodiments of FIG. 1 and FIG. 2. In a stillfurther embodiment of FIG. 6, there is arranged another barrier layer 5also inside the main body portion 1 as an inner layer in the embodimentof FIG. 5. Further, in yet another embodiment of FIG. 7, there is alsoarranged another adhering layer 4 between the main body portion 1 andthe barrier layer 5 inside it in the embodiment of FIG. 6. Moreover, itis also possible to provide a layer including a known oxygen absorbent.Depending on the usage, the constitution of the layers can beappropriately modified in a manner different from the above, and nolimitations are particularly imposed in this respect.

It is desirable that the thickness of the colored layer is varied withina range of 50% of the full thickness of the laminated and molded body.The reason therefor is the wall thickness variability and the externalappearance of the colored layer. In addition to the provision of thegradation effect for the molded body based on the wall thicknessvariation of the colored layer, it is also possible to constitute themolded body by also providing the main body portion with anothergradation effect.

FIG. 8 and FIG. 9 exemplarily show a blow molded article in a shape of adual-layered bottle-type container according to a yet further embodimentof the present invention, wherein the same reference numerals used inFIG. 1 and FIG. 2 are to denote identical or corresponding constituentelements. In this embodiment, the main body portion 1 is provided withthe colored layer 2 only over a half of a circumference of the main bodyportion 1 in its circumferential direction, and is not provided with thecolored layer 2 over the remaining half of the circumference. Thecolored layer 2 is arranged outside and integrally with the main bodyportion 1. As shown in FIG. 9, the thickness of the colored layer 2 isgradually increased from its one end portion toward its central portion,and is gradually reduced from its central portion toward its other endportion. Thus, the colored layer 2 exhibits such a circumferentialgradation effect that the color tone is deepened from the one endportion toward the central portion and is lightened from the centralportion toward the other end portion.

Note, the laminated and molded body shown in FIG. 8 and FIG. 9 can bemolded, such as by adopting a substantially crescent shape of a crosssection of the flow passage at a portion for merging the resin materialcorresponding to the main body portion 1 as the inner layer with theresin material corresponding to the colored layer 2. Meanwhile, if thereis provided appropriate controlling means for increasing/decreasing thesectional area of the flow passage at the merging portion in a timewisemanner, it becomes possible to appropriately increase/decrease thethickness of the colored layer 2 not only in a direction intersectingthe extruding direction but also in a direction parallel to theextruding direction, thereby making it possible to embody variousgradation patterns.

FIG. 10 shows another embodiment of the present invention in which thethickness of the colored layer 2 is increased and decreased in twodirections consisting of a direction intersecting the extrudingdirection and another direction parallel to the extruding direction.

As apparent from the above and according to the present invention, itbecomes possible to easily and assuredly obtain a laminated and moldedbody having an improved aesthetic appearance, only by adjusting thesupplying amount of the resin material forming the colored layer uponcoextrusion. Further, the full thickness “t” of the laminated and moldedbody is kept substantially constant over the whole of the laminated andmolded body even when the thickness of the colored layer is varied.Thus, there is never caused locally increased or decreased wallthickness, thereby making it possible to obtain a molded article havinga quality stabilized in terms of strength and to provide a laminated andmolded body having an enhanced gradation effect with a restricted cost.

Although the present invention has been explained with reference to thepreferred embodiments, it is apparent that the present invention can beperformed in various configurations other than the above, withoutdeparting from the scope of the present invention.

1. A laminated and molded body obtained by coextruding and molding atleast two kinds of resin materials, characterized in that at least onelayer of said laminated and molded body comprises a colored layer havinga thickness continuously or intermittently varied in a predetermineddirection with respect to the extruding direction of the resin materialof said colored layer.
 2. The laminated and molded body of claim 1,characterized in that the predetermined direction is a directionparallel to the extruding direction of said at least one layer of saidlaminated and molded body.
 3. The laminated and molded body of claim 1,characterized in that the predetermined direction is a directionintersecting the extruding direction of said at least one layer of saidlaminated and molded body.
 4. The laminated and molded body of claim 1,characterized in that the predetermined direction comprises a directionparallel to the extruding direction of said at least one layer of saidlaminated and molded body and another direction intersecting theextruding direction.
 5. The laminated and molded body of claim 1,characterized in that the full thickness of said laminated and moldedbody is substantially constant along said predetermined direction. 6.The laminated and molded body of claim 1, characterized in that saidcolored layer has a thickness varied within a range of 50% of the fullthickness of said laminated and molded body.
 7. The laminated and moldedbody claim 1, characterized in that said laminated and molded body is ablow-molding aimed preform, a direct-blow molded bottle, a tube, or ablow molded tube.
 8. A manufacturing method of a laminated and moldedbody to be formed by coextruding at least two kinds of resin materials,characterized in that said method comprises the steps of: extruding acolored layer as at least one layer of said laminated and molded body,and controlling an extruding amount of the resin material of saidcolored layer such that said colored layer has a thickness continuouslyor intermittently varied in a predetermined direction with respect tothe extruding direction of the resin material of said colored layer. 9.The manufacturing method of claim 8, characterized in that thepredetermined direction is a direction parallel to the extrudingdirection of said at least one layer of said laminated and molded body.10. The manufacturing method of claim 8, characterized in that thepredetermined direction is a direction intersecting the extrudingdirection of said at least one layer of said laminated and molded body.11. The manufacturing method of claim 8, characterized in that thepredetermined direction comprises a direction parallel to the extrudingdirection of said at least one layer of said laminated and molded bodyand another direction intersecting the extruding direction.
 12. Themanufacturing method of claim 8, characterized in that saidmanufacturing method further comprises the step of: controlling anextruding amount of the resin material of at least one layer other thansaid colored layer such that the full thickness of said laminated andmolded body is substantially constant along said predetermineddirection.
 13. The manufacturing method of claim 8, characterized inthat said manufacturing method further comprises the step of:controlling the extruding amount of the resin material of said coloredlayer such that said colored layer has a thickness varied within a rangeof 50% of the full thickness of said laminated and molded body.
 14. Themanufacturing method of claim 8, characterized in that said laminatedand molded body forms a blow-molding aimed preform, a direct-blow moldedbottle, a tube, or a blow molded tube.